S&P Global has agreed to acquire a majority stake in pan-African ratings agency Agusto & Co, seeking to deepen its presence in Africa's domestic credit markets, it said on Tuesday.

Agusto & Co will continue to operate as a separate ratings entity, issuing its own credit ratings and methodologies. The business has operations in Nigeria, Kenya, Rwanda and Ghana.

African governments and institutions have stepped up criticism of global rating agencies, accusing them of bias against the continent. The African Union and others have said African countries receive unfairly low ratings, pushing up borrowing costs and slowing development.

Moody's and S&P have rejected accusations of bias.

The deal is subject to regulatory approvals and is expected to close in the second half of this year. Financial terms were not disclosed.